Press fit vs. X-type BB

I just picked up a new 2011 Trance x1...super stoked on the purchase, got a great deal from the LBS.

I was previously running the SLX crank/x-type BB on my old hardtail. The Trance comes with the Deore XT crank/press fit BB. It is my understanding that XT is "better" (higher in the Shimano line) than SLX. However, I was also under the impression that the x-type BBs were the way to go. Probably a question I should have asked at the LBS but I was so excited after my test ride that the question faded from the front of my brain.

On the Shimano setup, my understanding is that the only difference is no threads on the bearing cups/carriers. Almost exactly the same otherwise. You could swap your cranks between the bikes and they would work fine.